China flexes its military muscle after ruling over disputed waters
China has raised tensions in the South China Sea by threatening to declare an air defence identification zone (ADIZ) over disputed waters where a tribunal has quashed its legal claim.
The Permanent Court of Arbitration in The Hague ruled on Tuesday that China had "no legal basis" for its 'nine-dash line', which lays claim to almost all of the South China Sea.
After considering a case brought by the Philippines, it ruled against China on virtually every substantive point. President Xi Jingping said China "refused to accept" the decision.
Yesterday, Liu Zhenmin, the vice foreign minister, said: "If our security is being threatened, of course we have the right to demarcate a (air defence identification) zone."
If such an ADIZ were to be imposed, China would require all aircraft entering the designated airspace to identify themselves.
China declared an ADIZ over disputed islands in the East China Sea in 2013, escalating tensions with the United States and Japan.
America responded by sending two B52 bombers through the ADIZ, without identifying themselves to China.
A new ADIZ in the South China Sea could provoke a similar response. It would also increase tensions not only with the Philippines, but also with other rival claimants in the South China Sea, including Brunei, Malaysia and Vietnam.
The ruling by the court in The Hague provided powerful diplomatic ammunition for China's Asian rivals in their dispute with Beijing over the South China Sea.
As well as declaring that China's historic claims had no legal standing, the court also denounced the environmental damage inflicted by Beijing's programme of creating artificial islands in the area, which have destroyed coral reefs and disrupted fishing and oil exploration.
Nonetheless, Mr Liu insisted that most of the South China Sea, including the Spratly and Paracel island chains, were China's "inherent territory".
He added: "We hope other countries will not take this opportunity to threaten China and will work with China to protect the peace and stability of the South China Sea and not let it become the origin of a war."
The court in The Hague has no power to enforce its rulings. But the resounding victory for the Philippines could spur other nations to bring their own cases against China.
Arthur Ding, a military expert based at Taiwan's National Chengchi university, said: "China will be watching closely the reaction of other countries - particularly Vietnam."
The ruling is binding but the Permanent Court of Arbitration has no powers of enforcement.
The Philippines' defence secretary Delfin Lorenzana said he had spoken to his US counterpart Ash Carter ahead of the ruling, who told him China had assured the United States that it would exercise restraint and the US made the same assurance.
Mr Carter had sought and been given the same assurance from the Philippines, Mr Lorenzana added.
"The ruling can serve as a foundation on which we can start the process of negotiations, which hopefully will eventually lead to the peaceful settlement of the maritime dispute in the South China Sea," Charles Jose, a spokesman for the Philippines' Department of Foreign Affairs, said.